you'll basically be fine.
the days will definitely be shorter and the weather a little colder than the summer months, potentially really cold on high descents, and it might be a bit wetter too. so plan accordingly: shorter rides, warmer gear.
i guess you're silently worrying about snow. not that likely.
If you hit a spell of good weather, it will be amazing not having to battle the heat on climbs. And if you hit a spell of cold weather, be a bit creative and use lower climbs.
he needn't be too worried for the reason I gave in my post: because it isn't particularly likely to snow in a way that should bother him.
Sure it sometimes snows quite low even in the summer (where were your mates caught out?) and a little bit more so in October, but not often or predictably enough to warn someone off booking a holiday just in case! Most of the ski resorts will report their "first snowfall" in November, and sometimes into December.
jimmythecuckoo - browse the archives on cycling-challenge.com for october 2007-8-9 and see what you think. Start here: http://www.cycling-challenge.com/col-do ... and-above/
I don't know where you are getting your info from
When in October was the OP thinking of going? If it's middle to end I would suggest forget it.
If it helps, the French word for the snow/rain line os 'isotherme' so a search on isotherme might come up with useful historical data.